[3.5] How could I adapt King Hassan (FGO) in the most accurate way possible?

[Tmenos9]

I am currently designing a campaign (it is not based on the type moon series) and I want to use a character that has always fascinated me.

As good lords of the dungeon that we are here, we know the armors and stealth combine as much as milk and lemon, I wanted to know if they had some ideas ...

Currently I have it designed as a swordsage with a few levels of warrior.

But he needs more.

If anyone knows the story of the character (based on the history of FGO) the build it is very low power, he is the instakiller, the assassin king.

If someone here plays the saga or knows what he is talking about, I would like to hear ideas on how to create this mass of force with armor but even being a furtive character

Thanks so much.

[awaken_D_M_golem]

Stealth + armor is do able.

Iron Heart Surge can handle some of the immunities.

" ... with a few levels of warrior ... "
Warrior as in what class ??
I'm assuming a very minor translation problem.

[TC X0 Lt 0X]

It is an NPC, so he might be using the NPC class Warrior to beef up the stats a bit, but otherwise, I would imagine Fighter.

From what I know about King Hassan, one of his skills has a small chance every strike to instant kill. A Vorpal Weapon would work to represent that easy enough though, and using the Literal Assassin class for this Assassin Class Servant for Death Strike doesn't seem to bad if not unoptimal, though if you build him to a high enough level then there are save or die maneuvers too.